WO2006131616A1

WO2006131616A1 - New type of molecular junction between a semiconductor and a metal

Info

Publication number: WO2006131616A1
Application number: PCT/FR2006/001178
Authority: WO
Inventors: Daniel Michelet
Original assignee: Daniel Michelet
Priority date: 2005-06-06
Filing date: 2006-05-23
Publication date: 2006-12-14
Also published as: FR2886643B1; FR2886643A1

Abstract

The invention relates to a new type of molecular junction in which molecules belonging to the families of 7-dialkylamino phenothiazines, 7-dialkylamino phenoxazines and of 5-alkyl or 5-aryl, 7-dialkylamino phenazines are grafted to a semiconductor by establishing a covalent bond between their carbon 3 and a surface atom of a semiconductor that can be a silicon atom, arsenic atom or germanium atom, and in which a metal is then electrolytically deposited onto the grafted surface of the semiconductor. The invention also relates to a new type of molecular junction in which the grafting of preceding organic molecules to a semiconductor is followed by the polymerization of an acrylonitrile or of N-vinyl-imidazole forming a polymer connected by a covalent bond to the grafted molecules and in which a metal, preferably copper, is then electrolytically deposited onto the grafted surface of the semiconductor. The inventive devices are particularly used for producing new types of electronic components and for realizing copper deposits in the submicronic semiconductor structures.

Description

NEW TYPE OF MOLECULAR JUNCTION BETWEEN A SEMICONDUCTOR AND A METAL

The present invention relates to a novel type of molecular junction. The term molecular junction refers to devices in which electrons are transported from one electronic conductor to another through a monolayer of organic molecules, or through a layer of organic molecules whose thickness does not exceed that of a few monolayers. organic molecules, about 20 Å. Such devices are expected to have varying intensity-potential characteristics i = f (V) depending on the structure of the molecules constituting the layer of organic molecules placed between the electronic conductors. If such an objective were achieved, molecular junctions could become the building blocks of a new type of electronic component. Numerous devices of this type have already been made in which the electronic conductors are either metals such as gold, mercury and titanium, or metalloids such as carbon and silicon, and in which the monolayers of molecules organic are either self-assembled or covalently grafted onto the surface of one of the electronic conductors (Chem.Mater., 2004, 16, 4477-4496).

In the embodiments described, a layer of organic molecules whose thickness represents 1 to 2 monolayers is developed on one of the electronic conductors, then the other electronic conductor is generally deposited by evaporation under high vacuum {Ânal.Chem ., 2004, 76, 1089-1097; Chemical Physics Letters, 2003, 203-204, 198-200) In most cases, the organic layer of aliphatic or aromatic carbides or azobenzene has been altered or destroyed, and the deposited metal has formed a short circuit. with the first electronic driver. Evaporation of metals under vacuum would be a fortiori more destructive for more complex organic structures than carbides, and is therefore not suitable. A means of depositing the second electronic conductor on the layer of organic molecules while preserving said layer remains to be found.

In the molecular junctions envisaged so far, the organic molecules placed electrically in parallel between the two electronic conductors carry electrons independently of each other. Electron transport must be through the lower energy unoccupied orbital (LUMO) and the higher energy occupied orbital (HOMO) organic molecules, according to the principle established by Aviram and Ratner in 1974. During the transfer of electrons by organic molecules, the organic layer must be electrically charged between the two electronic conductors, which would explain the increasing surge in electron transfer that has been observed when the intensity increases (J.Phys Chem. B ₁ 2002, 106, 10355-10362; Electrochemical and Solid-Sates letters, 2002, 5, E 43-E 46). Moreover, the molecules used up to now are not reversible low energy redox systems. , so that the repetition of the transfer of electrons by their molecular orbitals generates reactive intermediates which lead to the irreversible alteration of these molecules. The electrochemical reduction of aromatic diazonium salts on a carbon or silicon surface makes it possible to form molecular layers covalently attached to these surfaces. On carbon surfaces, the growth of the molecular layer is rather a nucleation process, and does not provide a continuous monolayer. On the other hand, on the hydrogenated silicon surfaces, in particular those of Si (111), it has been shown that the electrochemical reduction of diazonium salts could give rise to an ordered monolayer (J. ElectroanalChem., 2003, 550-551, 161-174 )

It has furthermore been shown that carbon surfaces, such as carbon black and carbon nanotubes and iron surfaces can be grafted spontaneously by simple contact with a solution of an aromatic diazonium salt (USP 5,554,739; 5,672,198). 5,698,016; 5,713,988; 5,885,355 and 6,110,994 to Cabot Corp., Chem.Mater.2001,13,3383; J.Am.Chem.Soc., 2001,123,4541). The hydrogenated compounds could also be grafted by contact with a solution of diazonium salt in acetonitrile, and the surface hydrogenosilanes reducing the diazonium salt (US 2004/0023479 A1 of 03/02/2003, J. Am Chem Soc. 2004, 126, 370-378) The reduction. Electrochemical or spontaneous diazonium salts on hydrogenated silicon surfaces can give rise to the formation of multiple molecular layers. The formation of these multiple layers can be decreased during the electrochemical reduction of diazonium salts on Si

(111) hydrogenated by controlling the reduction potential and the electric charge passed, or by the addition of BHT, an inhibitor of radical reactions, during the spontaneous grafting of hydrogenated Si (111) with a diazonium salt in acetonitrile.

Obtaining semiconductors whose surface is hydrogenated is known per se. In the case of silicon, it consists, for example, in treating its surface with a mixture of sulfuric acid and hydrogen peroxide, and then after rinsing with a 40% solution of ammonium fluoride.

This results in the formation of surface hydrogenosilanes whose density is, for example,

7.8 / nm ² in the case of silicon (111)

Obtaining diazonium salts by diazotization of primary amines is known per se.

A first object of the present invention resides in semiconductors carrying at their surface organic molecules D endowed with particular redox properties, connected to the surface of the semiconductor by a covalent bond, and whose association can form an organic conductor. two-dimensional on the surface of the semiconductor.

A second object of the present invention resides in semiconductors carrying on their surface D-PoI molecules with redox properties, connected both to the surface of the semiconductor and to a polymer -PoI comprising nitrile or imidazole groups.

A third object of the present invention resides in a new type of molecular junction constituted by a semiconductor carrying on its surface the D or D-PoI molecules, and a metal layer formed on said molecules.

A fourth object of the present invention is a novel type of barrier and priming layer for the electrolytic deposition of copper in submicron semiconductor structures, as well as in the method for obtaining said layer, in which a layer of D-PoI molecules will first form the submicron semiconductor surface, and then copper is deposited electrolytically.

More specifically, the present invention firstly relates to semiconductors (SC) carrying on their surface a layer of organic molecules (D) connected to the semiconductor by covalent bonds, said molecules being able to be in two oxidation states. SC-D ⁺ and SC-D ", characterized in that the semiconductors carrying the organic molecules correspond to the general formula:

SC-D ⁺ in proportion x SC-D "in proportion (1-x) in which:

SC denotes a surface atom of the semiconductor which may be a silicon or germanium or arsenic atom.

X denotes the following atoms or groups of atoms: O; S; NH or NR, wherein R denotes a linear alkyl group having 1 to 3 carbon atoms or a phenyl or para-tolyl group. - R ₁ , R ₂ , R ₄ , R ₀ , R ₈ , R ₉ , identical or different represent H or the methyl radical.

The groups R ₁ and R ₂ can form with the carbon atoms to which they are attached a benzene ring.

- Rn and Ri ₂ identical or different represent linear alkyl groups having 1 to 3 carbon atoms.

- A ^"represents Panion conjugate of any strong acid, which can be tetrafluoroborate, chloride or bromide.

x is between 0 and 1

More preferably, the semiconductor SC is silicon, and the organic molecules D are derived from dyes of the general formula D ⁺ -NH ₂ taken from the group formed by:

- X = S; R 1 = R ₂ = R ₄ = R ₆ = R ₈ = R ₉ = H, R _n ≈ R ₂ = methyl, derived from Azure A.

- X = S; R _J = R ₄ = R ₆ = R ₈ = R ₉ = H; R ₂ ≈ methyl; R ₁₁ = R ₁₂ ≈ methyl, derived from Toluidine Blue.

- X = O; Ri and R ₂ forming a benzene ring with the carbon atoms to which they are connected, R ₄ = R ₆ = R ₈ = R ₉ = H; R ₁ = R ₂ = ethyl; deriving from NiIe Blue.

- X = O; R 1 = R ₄ = R ₆ = R ₈ = R ₉ = H; R ₂ = methyl; Ri ₁ = R ₁₂ = ethyl, derived from Brilliant Cresyl Blue ALD

- X = NH; R 1 = R ₄ = R ₆ = R ₈ = R ₉ = H; R ₂ = methyl; Rn = R ₁₂ = methyl, derived from Neutral Red

X = N-phenyl; R 1 = R ₂ = R ₄ = R ₆ = R ₈ = R ₉ = H; Rn = Ri ₂ = ethyl, derived from Methylene Violet 3RAX

In a first mode, dyes having the general formula D ⁺ -NH ₂ , A ^"

wherein X, R 1, R ₂ , R ₄ , R ₆ , R ₈ , R ₉ , R ₁₁ , R ₁₂ , and A ^" have the meanings given on pages 2 and 3 at lines 102 to 111, are diazotized in 0.25 M / l sulfuric acid containing 0.0002 M / l of bromide ions according to the indications given in Analusis, 1999, 27, 174-180 The diazonium salt is then precipitated and then isolated in the form of tetrafluoroborate of formula D ⁺ -N ₂ ⁺ , 2BF ₄ ^" by addition of a concentrated solution of sodium tetrafluoroborate.

In a second embodiment, dyes corresponding to the general formula D ⁺ -NH ₂ , BF ₄ ^" indicated above are treated with 1.1 equivalents of BF ₄ NO at -20 ° C. in acetonitrile, and then, after heating, the diazonium salt of formula D ⁺ -N ₂ ⁺ , 2BF ₄ ^" is isolated by precipitation by addition of an ether.

Anhydrous diazonium salt is then dissolved in a solvent, preferably polar and ajprotique such as for example acetonitrile, at a concentration of entrelO ^"M / 1 and ^{10" 2} M / 1, preferably between 10 ^"4 M / and 1 ^'10 ^"3 M / 1, and this solution was degassed with nitrogen or argon. The hydrogenated surface of a semiconductor is then immersed in this solution, or covered by a film of this solution at a temperature between 0 ° C. and 70 ° C., preferably between 20 ^° C. and 50 ^° C. for a duration of between 15 minutes and 3 hours, preferably between 45 minutes and 2 hours, to carry out the grafting of the D molecules.

In a first preferred grafting mode, an inhibitor of radical reactions, of phenolic type, such as, for example, BHT, is added to the diazonium salt solution. The concentration of the inhibitor is between 10 ^-3 M / 1 and 0.5 M / 1, preferably between 10 ^-2 M / 1 and 0.1 M / 1. The role of the inhibitor is to intercept aryl radicals that have not reacted with the surface of the semiconductor to prevent them from reacting with molecules already grafted and then form layers of multiple organic molecules. In a second preferred grafting mode, in a novel manner according to the present invention, a base which is inert with respect to the diazonium salts such as, for example, 2,6 di-tert, is added to the diazonium salt solution. butyl-pyridine, or else 2,4,6-tri-tert-butyl pyrimidine at a concentration of between 10 ^-4 M / 1 and 0.5 M / l, preferably between 10 ^-3 M / 1 and 10 ^{'. 2} M / 1. The solution obtained is then cooled to a temperature between -30 ^° C. and 10 ^° C., preferably between -15 ° C. and 0 ^° C., and the surface of the semiconductor is brought into contact with this solution, the temperature of which is is kept constant. The role of the base is to accelerate the grafting reaction by fixing the redox potential of the surface of the hydrogenated semiconductor and to neutralize the tetrafluoroboric acid formed by the grafting reaction. In a third preferred method of grafting, the new conditions of the second preferred grafting mode are used, and after the solution has been cooled, the radical-free radical inhibition inhibitor of the first mode is added to the diazonium salt solution. preferred grafting. In a fourth grafting mode, a support salt is added to the diazonium salt solution, for example tetrabutylammonium tetrafluoroborate at a concentration of 0.1 M / l. The resulting solution is used as an electrolyte in an electrolyser in which the surface hydrogenated semiconductor is placed as a cathode. The grafting of the semiconductor surface by the molecules D takes place by cathodic polarization by following the procedure described in Journal of Electroanalytical Chemistry, 2003, 550-557, 161-174 with advantageously one and / or the other of the following modifications:

An inhibitor of radical reactions as defined on page 3 is added to the electrolyte at lines 159 to 164. The temperature is set at a value between 0 ^° C. and -30 ^° C., preferably between -10 ^° C. and -20 ⁰ C during the cathodic polarization of the semiconductor. It is preferable in all cases to carry out the grafting reaction of the D molecules on the semiconductor at the lowest possible temperature. Indeed, the D molecules are all the more likely to be disposed in the ordered cofacial manner sought in the present invention that the grafting reaction takes place at a lower temperature.

The progress of the grafting reaction can be measured as a function of time, for example by following the disappearance of the Si-H bonds at the silicon surface by measuring their infra-red absorption at v = 2083 cm ^-1. observing if multiple layers were formed by TOF-SIMS.

The D molecules grafted onto the semiconductors according to the present invention constitute reversible mono-electronic redox systems SC-D ⁺ / SC-D 'The reducing nature of the hydrides on the surface of the semiconductor, in particular that of the hydrogenosilanes, is increased by presence of the bases of the invention as defined on page 4 lines 165 to 169, and can be modulated according to their concentration. As a result, initially grafted molecules in the SC-D ^{+ form} are rapidly reduced to the SC-D "state by the surface hydrogenosilanes in the second and third preferred modes of grafting.The same reduction takes place by cathodic reduction. from SC-D ⁺ to SC-D 'in the fourth grafting mode The π interactions of the SC-D- molecules with each other and with the unreduced SC-D ⁺ molecules produce a two-dimensional organic conductor on the surface of the semi -conductor, said organic conductor representing the first object of the present invention, particularly on the surface of silicon and more specifically on the surface of silicon (111)

The formation of an organic conductor whose orbital are delocalized over a large part of the grafted organic layer promotes the transfer of electrons between the semiconductor and this organic conductor and solves the problem encountered so far with the molecular junctions in which each transmitted electron was localized on a single molecule of the organic layer, whereas in the device of the present invention, the electrons transmitted are delocalized on a large number of molecules constituting a two-dimensional organic conductor.

To obtain the semi-reduced SC-D 'shape favorable to the constitution of a two-dimensional organic conductor on the surface of the semiconductor, it is preferable to carry out the grafting reactions of the molecules D of the invention on semi-conductors. -conductors in .aprotic solvents, because a protic solvent could lead to the formation of reduced forms SC-DH less favorable.

The second subject of the present invention is semiconductors bearing at their surface organic molecules characterized in that said organic molecules have the formula SC-D-PoI ₅ in which the molecules D, the first subject of the present invention, are linked together. by covalent bonds, both to the semiconductor and to a polymer -PoI comprising nitrile and / or imidazole functions.

The semi-reduced SC-D 'form of the grafted molecules can initiate the polymerization of acrylic or vinyl monomers. Preferred monomers for the preparation of molecular junctions and for the preparation of barrier and priming layers in submicron semiconductor structures are acrylonitrile, methacrylonitrile and N-vinylimidazole. In a first mode, the surface of the semiconductor carrying the SC-D molecules of the invention is immersed in, or covered by, a solution containing a monomer, or a mixture of the monomers at a total concentration of these monomers between 0 , 1 to 1QMIl, preferably between 0.5 and 2 M / 1 at a temperature between 0 ⁰ C and 100 ° C, preferably between 20 ⁰ C and 70 ⁰ C.

In a second embodiment, the semiconductor carrying on its surface the SC-D molecules of the invention is exposed to vapors containing a monomer or a mixture of the monomers at a temperature of between 20 ^° C. and 130 ^° C., preferably between 50 ⁰ C and 100 ⁰ C. In a third embodiment, the semiconductor carrying the SC-D molecules of the invention is placed as a cathode in an electrolyzer whose electrolyte is constituted by acrylonitrile, methacrylonitrile or by their mixtures, at a total concentration of between 10 ^-2 M / 1 and 1 M / l in solution in an aprotic solvent containing a conductive salt, such as, for example, in acetonitrile containing a tetrabutyl ammonium salt. of the cathode is then brought to a value of about -1 VTENH which has the effect of generating the reduced SC-D ^" anionic form of the SC-D molecules of the present invention, which initiates anionic polymerization of the acrylic monomers and produces the SC-D-PoI molecules, the first monomer of the polymer PoI being linked by a covalent bond to the N _1O nitrogen atom of the SC-D molecules

The third subject of the present invention is molecular junctions comprising a semiconductor characterized in that said semiconductor carries on its surface a layer of the SC-DVSC-D ⁺ or SC-D-PoI molecules, said molecules representing the first two objects of the present invention, a layer on which a metal layer is formed. Any mode of formation of the metal layer which does not alter the D molecules may be suitable, and the resulting molecular junctions are part of the invention. According to a preferred embodiment, the metal layer is formed by electrolytic deposition. This deposition mode gives rise to an easily controllable process which takes place in the liquid phase at atmospheric pressure and can be linked with the prior steps of developing the molecular junctions which also take place in the liquid phase according to the present invention. Metal layers consisting of transition metals, heavy metals, or their alloys are suitable. For example, metal layers made of copper, palladium, silver, gold, tin, indium, lead, bismuth, chromium, cobalt, zinc, cadmium and than their alloys.

The thickness of the deposited metal layer may vary from 3 to 50 nm, after which electroplating may be continued in the same mode, or by challenging commercial electrolytic baths.

When using a semiconductor carrying on its surface the SC-D 'and SC-D ⁺ molecules produced according to the invention, it is preferable to electrolytically deposit the metal or metal alloy from non-aqueous electrolytes. consisting of aprotic solvents. Particularly preferred are electrolytes consisting of nitriles, especially acetonitrile.

The preferred metal salts are triflates, tetrafluoroborates, hexafluorophosphates, bis (trifluoromethylsulfonyl) imidates. Complex metal salts with nitriles can be used, for example tetrakis hexafluorophosphate (acetonitrile) copper

(I) or tetrakis (acetonitrile) palladium (II) tetrafluoroborate

The salt ensuring the conductivity of the electrolyte is a tetraalkylammonium salt, or a lithium salt associated with an anion such as the anions of the metal salts mentioned above. The anode consists of the metal or alloy corresponding to the electrodeposited metal layer.

In a preferred embodiment, after a metal layer corresponding to a thickness of 2 nm to

10 nm was deposited, without interrupting the electrolytic deposition is added 5 to 50 ppm of thiourea electrolyte in order to obtain a smoother metal deposition.

When using a semiconductor carrying on its surface the SC-D-PoI molecules produced according to the present invention, the metals or their alloys can be electrolytically deposited on said molecules from non-aqueous electrolytes as described. above, but also from aqueous electrolytes which are preferred in this case. Particularly suitable are aqueous electrolytes containing salts whose cations are complexed with nitrile and imidazole groups, such as the copper (I), silver (I) gold (I) and palladium (II) salts. semiconductors carrying the SC-D-PoI molecules of the invention are brought into contact with electrolytes containing said salts, the polymer PoI then saturates with metal cations complexed by the nitrile and imidazole groups that comprises said polymer. When the semiconductor is then brought to a cathodic potential, these cations complexed by the polymer are reduced to the metallic state while the corresponding flag is expelled from the layer of SC-D-PoI molecules in the electrolyte.

This results in a SC-D- (metallized PoI) structure in which the layer of D molecules grafted to the semiconductor is bonded to a metallized polymer which is an electronic conductor. In the resulting molecular junction, electrons can be exchanged between a semiconductor and a metallized polymer through a grafted organic molecule layer of the invention.

In a preferred embodiment, the metal salt used is cuprous sulfate complexed with a nitrile. The preferred nitriles are acetonitrile and 3-hydroxypropionitrile which may comprise from 2% to 50%, preferably from 10% to 25% by weight of the electrolyte. The concentration of cuprous ions can be between 0.1 M / 1 and 2M / 1, preferably between 0.4 M / 1 and 1 M / 1. The electrolyte can be advantageously prepared by adding the nitrile to an aqueous solution of cupric sulfate, and then contacting said solution with an excess of copper powder as described in Pure and Applied Chemistry, 1981, 53, 1437. The electrolytic deposition of the copper can be continued after the formation of the metallized polymer layer to form a metal layer with a thickness of for example between 100 nm and 1 micron which can make it possible to establish one of the electrical contacts of the junction molecular. To obtain a copper deposit of satisfactory appearance can be added to the electrolyte from 10 ppm to 100 ppm of gelatin and from 10 ppm to 100 ppm of thiourea, and perform the deposition under agitation of the electrolyte with a current density between 2 mA / cm ² and 15 mA / cm ² , preferably between 5 mA / cm ² and 10 mA / cm ² Further details relating to the electrolytic deposition of copper with electrolytes of similar composition can be found in Hydrometallurgy, 1975, 1, 61-77, and 155-168.

The fourth subject of the present invention is stopping and priming layers for the electrolytic deposition of copper in submicron semiconductor structures, characterized in that said submicron semiconductor structures carry on their surface a layer of SC molecules. D-PoI representing the second subject of the present invention, and a copper layer on said layer of molecules

Such an object can be achieved by repeating with submicron semiconductor structures the same process that was followed to perform the molecular junctions, the third object of the present invention, with the proviso that the metal is copper and that the Electrode deposition method of copper described on pages 6 and 7 at lines 284 to 313 is applied. When a copper thickness of 2 nm to 10 nm has been deposited, a stop and start layer is formed in the submicron semiconductor structure according to the present invention. It is then possible either to continue the deposition of the copper in the submicron semiconductor structure in the same mode, or to continue the deposition of the copper with commercial electrolysis baths.

Claims

1-SC semiconductor carrying on its surface a layer of organic molecules D connected to the semiconductor by covalent bonds SC-D, said molecules connected to the semiconductor can be in two possible oxidation states SC-D ⁺ and SC -D ", characterized in that the semiconductor carrying the organic molecules corresponds to the general formula,

. (SC-D ⁺ ) in proportion x (SC-D ") in proportion (1-x) in which:

- SC denotes a surface atom of the semiconductor which may be a silicon atom or germanium or arsenic.

X denotes the atoms or groups of atoms of formula: O; S; NH; N-R, wherein R denotes a linear alkyl group having 1 to 3 carbon atoms or a phenyl or para-tolyl group.

- R ₁ , R ₂ , R ₄ , R, R ₈ , R ₉ _> identical or different represent H or the methyl radical.

R 1 and R _{1, which may be} identical or different, represent linear alkyl groups comprising from 1 to 3 carbon atoms.

-A ^" represents a conjugate of a strong acid, which may be a tetrafluoroborate, a chloride or a bromide

x is between 0 and 1

2- A semiconductor carrying on its surface a layer of organic molecules according to claim 1 characterized in that the semiconductor is silicon, and the organic molecules D bonded to the silicon surface are taken from the group consisting of:

- X = S; R ₁ = R ₂ = R ₄ = R ₆ = R ₈ = R ₉ = H; R _n = Ri ₂ = methyl.

- X = S; R ₁ = R ₄ = R ₆ = R ₈ = R ₉ = H; R ₂ = methyl R ₁₁ = R ₁₂ = methyl.

- X = O; R 1 and R ₂ forming a benzene ring with the carbon atoms to which they are attached; R ₄ = R ₆ = R ₈ = R ₉ = H; Ri 1 = R ₁₂ = ethyl.

- X = OJR ₁ = R ₄ = R ₆ = R _S = R _C = HJR ₂ = methyl; R ₁₁ = Ri ₂ = ethyl.

- X = NH; R ₁ = R ₄ = R ₆ = R ₈ = Rp = H; R ₂ = methyl; R ₁₁ = R ₂ = methyl - X = N-phenyl; R ₁ = R ₂ = R ₄ = R ₆ = R ₈ = R ₉ = H; R _n = R _{] 2} = ethyl

3- Process for obtaining a semiconductor carrying on its surface a layer of organic molecules according to claims 1 or 2, characterized in that the surface of the semiconductor in its hydrogenated form is covered for an effective period by a solution comprising a diazonium salt of the general formula,

wherein, X, R ₁ , R ₂ , R ₄ , R ₆ , R ₈ , R ₉ , R ₁₁ , R ₁₇ , and A ^" have the meaning given in claim 1

4- Process for obtaining a semiconductor carrying on its surface a layer of organic molecules according to claim 3, characterized in that the solution comprising the diazonium salt comprises an effective amount of 2,6 di-tert-buty pyridine, or 2,4,6-tri-tert-butyl pyrimidine.

5. Process for obtaining a semiconductor carrying on its surface a layer of organic molecules according to claim 3, characterized in that the semiconductor covered by the diazonium salt solution is cathodically polarized with respect to the solution. for an effective duration.

6- Semiconductor carrying on its surface a layer of organic molecules P connected to the semiconductor by covalent bonds, characterized in that the semiconductor bearing the organic molecules P corresponds to the general formula,

in which,

-SC, X, R 1, R ₂ , R ₄ , R ₆ , R ₈ , R ₉ , R ₁₁ and R ₁₂ have the meaning given in claim 1.

- PoI denotes an oligomer or a polymer of acrylonitrile, methacrylonitrile or N-vinyl-imidazole, or a co-oligomer, or a copolymer of these monomers.

7- Process for obtaining semiconductors carrying on their surface a layer of molecules P according to claim 6, characterized in that the semiconductors carrying on their surface a layer of molecules D according to claims 1 or 2 are contact of a solution comprising acrylonitrile, or methacrylonitrile, or N-vinylimidazole, or a mixture of these monomers at a temperature and for an effective time.

8- molecular junction constituted by a semiconductor layer of organic molecules and a metal layer characterized in that the semiconductor and the layer of organic molecules meet the formulas according to claims 1, 2 or 6.

9- Process for obtaining a molecular junction according to claim 8, characterized in that a metal layer is formed by electrolytic deposition on a semiconductor carrying a layer of organic molecules obtained by the processes of claims 3, 4, 5, or 7.

10- Process for obtaining a molecular junction according to claim 9, characterized in that the electrolyte comprises a copper salt at valence 1 in solution in acetonitrile.

11- Electronic components in which electrons are exchanged between a semiconductor and a metal via a molecular junction according to claim 8.

12- Process for obtaining a priming layer for the electrolytic deposition of copper in submicron semiconductor structures, characterized in that the surface of said submicron semiconductor structure is treated according to claims 1 or 2, and then according to claim 1, and a copper layer is electrolytically deposited on said treated surface.